Two blocks away from Liberty Bell.
Very nice kitchen, living room, sofas, bathroom, bedroom.
Eating was a little inconvenient:
either Bar stool/Kitchen counter or Sofa/Coffee table.
Caution:
the 42(?) stairs to the 3rd floor were steep, narrow, straight up with only one tiny landing at the only 2nd floor apt. door (the way down with heavy luggage was scary).
No washer/dryer in apt. or building, Laundromats are quite far away. We found a nice one on 5th St., just north of South St. (IM Laundromat).
Parking was expensive, hard to find, mostly prohibited; enforcement is aggressive (we got 3 parking tickets in less than 24 hours: $40+$45+$80 = $165).
Overall rating would have been 5 stars, if it weren't for the noticeable smell of weed in the apartment.
Public transit
Airport - Jefferson Station:
The Airport Line ran only once an hour (on a Tuesday afternoon!) and terminated at the Amtrak Station (on 30th Street), due to rail repairs. Then you walk a block outside to the Market-Frankford Lightrail Line (it's an underground station, entrance is small and hard to spot). Choose Direction Frankford and exit at Market St. & 8th St.